malachite


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malachite

(măl`əkīt), a mineral, the green basic carbonate of copper occurring in crystals of the monoclinic system or (more usually) in masses. It is translucent or opaque; the luster is silky, vitreous, adamantine, or dull. It takes a good polish. An important ore of copper, it also serves as a gem and for various ornamental purposes and, when finely ground, as a pigment. It is found associated with other ores of copper (especially azuriteazurite
, blue mineral, the basic carbonate of copper, occurring in monoclinic crystals or masses that range from transparent to translucent and opaque. It is usually associated with malachite, which it resembles except in color; when the two minerals are very closely
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) in various parts of the United States and in Chile, Russia, Congo (Kinshasa), Zimbabwe, and Australia.

Malachite

 

a carbonate mineral; composition Cu2[Co3] (OH)2 and containing 57.4 percent Cu. Additional (OH)1— anions in the crystalline structure of malachite are bonded to Cu2+ ions, which are surrounded in one plane by two (OH)1— and two O2+ ions belonging to the (CO3)2- carbonate anion. The most common admixtures are Zn (which isomorphically substitutes for Cu), CaO, SiO2, and Fe2O3.

Malachite crystallizes in the monoclinic system. Crystals, which are acicular or prismatic, are rare. Common formations of malachite are cryptocrystalline or microcrystalline reniform incrustations and stalactitic aggregates, which are evenly banded and divergently fibrous. Earthy malachite masses are known as green copper carbonates. The color of malachite ranges from bright green and bluish green to dark green and sometimes even brownish green. The changes that occur in color in the various zones and layers of reniform masses of malachite create very beautiful and fanciful designs along cut and polished planes. Malachite has a hardness of 3.5-4.0 on Mohs’ scale and a density of 3,900-4, 100 kg/m3.

In nature, malachite occurs in the upper oxidized zones of sulfide copper ores. Large accumulations of solid malachite are extremely rare and form during the replacement of limestone by copper sulfate in the oxidation zone of massive copper deposits. Such accumulations (up to 50 m) were worked in the Urals (in the vicinity of Nizhnii Tagil) during the 18th and 19th centuries; other deposits containing ornamental malachite are located in Chile. Solid malachite is a valuable ornamental material and is used to make jewelry and decorative objects (insets, beads, veneer for table tops, vases, column facings). Large articles are faced with thin malachite plates, which are matched according to design and pasted onto a matrix made of metal or other material (“Russian mosaic”). All ornamental objects and large articles are usually fashioned from Ural malachite (The Hermitage in Leningrad, various palace-museums in the USSR and other countries).

Earthy malachite and small accumulations of the pure mineral are used in the manufacture of the valuable paint known as malachite green. Malachite occurring in mixed oxidized ores is used in the smelting of copper.

G. P. BARSANOV

malachite

[′mal·ə‚kīt]
(mineralogy)
Cu2CO3(OH)2 A bright-green monoclinic mineral consisting of a basic carbonate of copper and usually occurring in massive forms or in bundles of radiating fibers; specific gravity is 4.05, and hardness is 3.5-4 on Mohs scale.

malachite

A carbonate of copper; green in color; harder than marble; usually employed as a highly polished veneer.

malachite

guards wearer from evil spirits, enchantments. [Gem Symbolism: Kunz, 97]

malachite

a bright green mineral, found in veins and in association with copper deposits. It is a source of copper and is used as an ornamental stone. Composition: hydrated copper carbonate. Formula: Cu2CO3(OH)2. Crystal structure: monoclinic
References in periodicals archive ?
Malachite green is an industrial dye and a disinfectant for gold fish.
All results reported from the quartz vein/gossan with malachite staining proved to be anomalous.
All anomalous results were reported from the quartz vein/gossan with malachite staining.
The test, conducted after China's southern Guangdong Province moved earlier this week to ban exports of eel products, found that 11 out of 14 samples contained malachite green, a common antifungal agent used in fish farming, Deputy Secretary for Health, Welfare and Food Eddy Chan said.
The restaurant, which has increased its seating capacity from 45 to 70, has been renovated by Coventry designer Richard Jones of Malachite Interiors, Albany Road.
Exploration will begin in April with the examination of Anaconda drill core to the south of the Malachite zone in preparation for prospecting in that area.
Malachite green, which we have talked about for a number of quarters, is still the main colour series this spring.
Once widespread throughout the south of England, the shy and retiring Scarlet Malachite Beetle is being sought when it appears briefly during May and June.
The Agri-Food and Veterinary Authority on Saturday ordered all eel products from China to be recalled from store shelves after it detected traces of residues of malachite green chloride, a chemical agent used to treat parasite and fungal infections in fish, in samples of eels from China, said Goh Shih Yong, spokesman for the authority.
Oxide mineralization comprising cuprite, malachite, azurite, limonite associated with 1-3% quartz veins was noted to a depth of 314m.
The copper mineralization consisting of disseminations and veinlets of malachite is exposed in outcrop over a distance of approximately 50 metres to the west and over a vertical distance of 15 metres.
Scottish salmon fillets containing the chemical malachite green were bought from the fresh fish counter at Morrisons in Byker, Newcastle, in February this year.